1. Field of Invention
The present invention relates to an image processing apparatus, an imaging apparatus comprising the same, and an image processing method.
2. Description of Related Art
As an imaging element which converts an optical image formed by an optical system into an electric signal, an imaging element in which some pixels are configured to output a signal for focus detection is known. For example, in Jpn. Pat. Appln. KOKAI Publication No. 2000-156823, in order to provide some of the pixels with a ranging function based on a pupil phase difference detection system, a technique is disclosed relating to an imaging element in which a part of a light receiving surface of the pixels is light-shielded. Information acquired by phase difference pixels having such ranging function is, for example, used in auto-focus processing which drives the optical system to an in-focus position. Jpn. Pat. Appln. KOKAI Publication No. 2011-124704 discloses a technique for performing gain correction computation on the information of phase difference pixels, and using the information obtained by the phase difference pixels for forming images for displaying or recording.
In phase difference pixels, it is preferable to perform appropriate exposure control for ranging. Therefore, under circumstances where it is difficult to obtain phase difference information, such as in dark places, a method in which an exposure time is made longer than that of normal pixels for acquiring image signals only for the phase difference pixels is suggested. However, if the exposure times of the phase difference pixels and the normal pixels are different, when photographing a moving object, a difference will occur in the image blurring amounts between the image acquired by the phase difference pixels and the image acquired by the normal pixels due to the difference in the exposure times. As in the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2011-124704, if information acquired by the phase difference pixels is used for an image for displaying or recording, image degradation may occur due to the difference in image blurring amounts being reflected in the generated image.